Sealing cover for a processing hole in aluminum sheet metal

ABSTRACT

The present cover is used for permanent sealing of an oval-shaped processing hole ( 7 ) in aluminum sheet metal ( 8 ) by means of an adhesive joint. The cover consists of a circular cover plate ( 1 ) of aluminum with a concentric cover edge ( 2 ) and a ring-shaped strip ( 3 ) of hot-melt adhesive applied within the cover edge ( 2 ). The interior region of the cover plate ( 1 ) is connected to a spring plate ( 5 ) aligned plane-parallel with the cover plate at a spacing of the thickness of the aluminum sheet metal ( 8 ). The outer edge ( 6 ) of the spring plate ( 5 ) has a contour that corresponds to the shape of the oval processing hole ( 7 ) and is somewhat smaller than the diameter of the hole ( 7 ).  
     In the most separated edge regions ( 10 ) of the spring plate ( 5 ) there are quarter-circular spring tongues ( 11 ) punched at their free ends which tongues are springily formed at one end to the spring plate ( 5 ). After insertion of the spring plate ( 5 ) into the processing hole ( 7 ) up to contact of the adhesive strip ( 3 ) on the aluminum sheet metal ( 8 ), the spring tongues ( 11 ) can be brought to a tight fit by spring force against the back side of the aluminum sheet metal ( 8 ) by a quarter turn of the cover plate, and due to the spring force exerted by the spring tongues ( 11 ), they produce the necessary pressure on the adhesive strip ( 3 ).

[0001] The invention pertains to a cover for permanent sealing of an oval-shaped processing hole in aluminum sheet metal by means of an adhesive joint. The cover consists of a circular aluminum plate with a concentric cover edge and a ring-shaped strip of hot-melt adhesive applied within the cover edge.

[0002] In the case of an automobile chassis manufactured from aluminum, there are a number of processing holes which have to be resealed by large covers after they are no longer needed. In order to seal the holes water-tight, it is useful to glue a cover made of the same aluminum material onto the hole by using a hot-melt adhesive. In this case it is necessary that the adhesive strip applied within the edge of the cover be about 0.5 to 0.7 mm higher than the edge of the cover. In addition, in order to save energy and time, it is useful for the adhesion process to be conducted in conjunction with the catalytic immersion bath lacquering of the aluminum chassis. Thus, the heating process after the immersion bath can be used at the same time for melting and hardening of the adhesive.

[0003] However, in this regard it is important that the cover be pressed onto the hole tightly around the aluminum plate and that it be held down until the adhesive has hardened. In order to achieve this, with regard to the cover formation described above, it is proposed that the interior region of the cover plate be connected to a spring plate aligned plane-parallel with the cover plate at a spacing of the thickness of the aluminum sheet metal, which spring plate outer edge has a contour that corresponds to the shape of the oval processing hole and is somewhat smaller than the perforated edge, that in the most separated edge regions of the spring plate at a spacing from its outer edge quarter-circular spring tongues that are springy at their free ends are punched, and that after insertion of the spring plate into the processing hole up to contact of the adhesive strip on the aluminum sheet metal, the spring plate with its spring tongues can be brought to a tight fit by spring force against the back side of the aluminum sheet metal by a quarter turn of the cover plate.

[0004] The cover designed according to this invention can be quickly and easily placed into and brought into contact with the processing hole by a rotation of 90° after introduction of the spring plate mounted to the underside of the cover. Thus, the cover will be securely held in place against the sheet metal by the spring tongues. Since no immersion bath fluid can get between the surfaces to be glued during the subsequent catalytic immersion bath lacquering, after melting and hardening of the adhesive in the subsequent heating process, a dependable connection is achieved in a simple manner, which moreover is mechanically secured by the spring tongues, and thus remains highly resistive even in case of stress.

[0005] Additional properties of the invention are indicated from the dependent claims in conjunction with the following description of the figures, which illustrate one design embodiment of the invention. We have:

[0006]FIG. 1 The cover plate of the sealing cover according to this invention, presented in top view

[0007]FIG. 2 A cross section through the cover plate along line II-II in FIG. 1

[0008]FIG. 3 The associated spring plate presented in top view

[0009]FIG. 4 The spring plate shown in side view

[0010]FIG. 5 The sealing cover ready for use and seen from below

[0011]FIG. 6 The sealing cover presented in cross section along line VI-VI in FIG. 5

[0012]FIG. 7 A partial cross section through the spring tongue along line VII-VII in FIG. 3

[0013]FIG. 8 A partial cross section through the connection point along line VIII-VIII in FIG. 5 after the pass-through joining process

[0014]FIG. 9 The sealing cover shown in perspective view, from below

[0015]FIG. 10 The sealing cover shown in perspective view, from above

[0016]FIG. 11 The oval processing hole shown in top view

[0017]FIG. 12 The sealing cover before introduction of the spring plate into the processing hole

[0018]FIG. 13 The sealing cover after introduction of the spring plate into the processing hole, and

[0019]FIG. 14 The sealing cover locked in position in the processing hole after a rotation by 90°.

[0020] The sealing cover illustrated in the figures consists of a circular cover plate 1 made of aluminum, with a concentrically beaded cover edge 2, which is used for a flush contact upon the aluminum sheet metal 8, and also of a spring plate 5 which can be joined to the cover plate 1 in a rotatably locked manner. After insertion into the processing hole 7 and after making contact with the protruding adhesive 3 to the aluminum sheet metal 8, this spring plate can be brought to rest against the back side of the sheet metal by a quarter turn.

[0021] Within the cover edge 2 there is a circular strip 3 made of a hot-melt adhesive and it is designed at a height such that this strip 3 extends above the cover edge 2 by about 0.5 to 0.7 mm. In the central region of the cover plate 1 there is a plane-parallel protrusion 4 which is molded on or pressed on and which serves as a support for the aforementioned spring plate 5. The distance ‘a’ between the support surface 4 and the cover edge 2 is a little greater than the thickness d of the aluminum sheet metal 8 to be covered by the cover plate 1 (see FIG. 8 [sic; 12]).

[0022] The outer edge 6 of the spring plate 5 illustrated in FIGS. 3 and 4 has a contour which corresponds to the shape of the oval processing hole 7 in the aluminum sheet metal 8 illustrated in FIG. 11, and is a little smaller than the perforated edge 9 of the processing hole 7. In the most separated edge regions 10 of the spring plate 5 and at a distance to its outer edge 6, there are some spring tongues 11 which are punched out in roughly quarter-circle shapes. They are formed on one end as spring-like protrusions against the spring plate 5. At the springy end of the spring tongues 11 there are bulges 12 (as seen in FIG. 7) stamped out in direction upon the cover plate 1. When the spring plate 5 is rotated in the processing hole 7, these bulges slide over the aluminum sheet metal 8 and thus generate a pretension (FIG. 14). Instead of the bulges 12, hemispherically-shaped knobs can also be used.

[0023] There are at least two holes 13 formed in the support surface 4 of the cover plate 1 and the spring plate 5 has the same number of drilled holes 14 at the same spacing from each other; these are intended for riveting the cover plate 1 with the spring plate 5, or for joining them by other means. The planar-parallel protrusion 4 is formed preferably with mutually parallel inner walls 15, which serve as contact surfaces for a correspondingly shaped caterpillar-shaped head of a turning tool and also act as the stop position for the quarter turn.

[0024] Instead of conventional riveting, the rotatably locked joint between the spring plate 5 and the support surface 4 can also be produced by a so-called pass-through joining process, for example (FIG. 8). The resulting recesses 16 in the support surface 4 can then also be used as contact surfaces for a turning tool equipped with corresponding pins.

[0025] FIGS. 12 to 14 present the single stages of preassembly of the sealing cover on the aluminum sheet metal. FIG. 12 shows the sealing cover before introduction of the spring plate 5 in the direction “E” of the arrow into the oval processing hole 7, which is visible in FIG. 11 in a top view. As soon as the spring plate 5 has been fully immersed into the hole 7 (as is visible in FIG. 13) and the adhesive strip 3 is resting upon the aluminum sheet metal 8, the sealing cover will be turned by 90° in direction “D” of the arrow by means of a tool engaging in the recess of the support 4. Thus, the spring tongues 11 with their bulges or knobs 12 at the springy end will run past the back side of the aluminum sheet metal 8 and generate the necessary pretension on the adhesive strip 3 by means of the spring force exerted by the spring tongues 11 in the direction “F” of the arrow (FIG. 14).

[0026] The sealing cover is now seated securely in the processing hole 7 and moves together with the aluminum sheet metal 8 into the oven and through the catalytic immersion bath lacquering. This will then melt the adhesive strip 3 due to the temperature of up to 200° C. prevailing in the oven and after hardening with the aluminum sheet metal 8, it will form a water-tight joint around the processing hole 7, while the sealing cover, after the melting of the adhesive strip 3, rests with its cover edge 2 against the aluminum sheet metal 8. 

1. Cover for permanent sealing of an oval-shaped processing hole (7) in aluminum sheet metal (8) by means of an adhesive joint, consisting of a circular cover plate (1) of aluminum with a concentric cover edge (2) and a ring-shaped strip (3) of hot-melt adhesive applied within the cover edge (2), characterized in that the interior region of the cover plate (1) is connected to a spring plate (5) aligned plane-parallel with the cover plate (1) at a spacing of the thickness of the aluminum sheet metal (8), which cover plate outer edge (6) has a contour that corresponds to the shape of the oval processing hole (7) and is somewhat smaller than the perforated edge (9), that in the most separated edge regions (10) of the spring plate (5) at a distance to its outer edge (6) quarter-circular spring tongues (11) that are springy at their free ends are punched, and that after insertion of the spring plate (5) into the processing hole (7) up to contact of the adhesive strip (3) on the aluminum sheet metal (8), the spring plate (5) with its spring tongues (11) can be brought to a tight fit by spring force against the back side of the aluminum sheet metal (8) by a quarter turn of the cover plate (1).
 2. Sealing cover according to claim 2 [sic], characterized in that bulges or knobs (12) on the other springy end of the spring tongues (11) are stamped in direction on the cover plate (1).
 3. Sealing cover according to one of claims 1 to 3 [sic], characterized in that in its middle region there is a plane-parallel protrusion (4) for support of the spring plate (5), and the distance ‘a’ between the protrusion surface (4) and the cover edge (2) is somewhat larger than the thickness d of the aluminum sheet metal (8).
 4. Sealing cover according to claim 4 [sic], characterized in that there are at least two holes (13) provided in the protrusion surface (4) and the spring plate (5) has the same number of holes (14) at the same spacing to each other for mutual riveting or joining.
 5. Sealing cover according to claim 4, characterized in that the cover plate (1) is manufactured from an aluminum sheet metal of about the same thickness as the aluminum sheet metal (8) to be covered, and that the plane-parallel protrusion (4) is molded with mutually parallel interior walls (15), which serve as contact surfaces for an accordingly shaped turning tool and also as stop-surface for the quarter-turn.
 6. Sealing cover according to claim 4, characterized in that the connection between the spring plate (5) and the protrusion surface (4) is provided by a pass-through joining process.
 7. Sealing cover according to claim 7 [sic], characterized in that the recesses (16) produced in the pass-through joining on the back of the protrusion surface (4) are used as contact points for a turning tool equipped with corresponding pins. 